* @param errorMessageTemplate a template for the exception message should the check fail. The
   *     message is formed by replacing each {@code %s} placeholder in the template with an
   *     argument. These are matched by position - the first {@code %s} gets {@code
   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.

        .isTrue();
    if (!failures.isEmpty()) {
      StringWriter message = new StringWriter();
      PrintWriter writer = new PrintWriter(message);
      writer.println("Expected no failures, but found:");
      for (AssertionError failure : failures) {
        failure.printStackTrace(writer);
      }
      failures.clear();
      assertWithMessage(message.toString()).fail();
    }
  }

   * are identical, even if the input set uses a different concept of equivalence.
   *
   * <p><i>Performance notes:</i> while the power set of a set with size {@code n} is of size {@code
   * 2^n}, its memory usage is only {@code O(n)}. When the power set is constructed, the input set
   * is merely copied. Only as the power set is iterated are the individual subsets created, and

      if (overWaitUnits > 0) {
        message += overWaitUnits + " " + unitString;
        if (shouldShowExtraNanos) {
          message += ",";
        }
        message += " ";
      }
      if (shouldShowExtraNanos) {
        message += overWaitLeftoverNanos + " nanoseconds ";
      }

      message += "delay)";
    }

   * @param errorMessageTemplate a template for the exception message should the check fail. The
   *     message is formed by replacing each {@code %s} placeholder in the template with an
   *     argument. These are matched by position - the first {@code %s} gets {@code
   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.

        .isTrue();
    if (!failures.isEmpty()) {
      StringWriter message = new StringWriter();
      PrintWriter writer = new PrintWriter(message);
      writer.println("Expected no failures, but found:");
      for (AssertionError failure : failures) {
        failure.printStackTrace(writer);
      }
      failures.clear();
      assertWithMessage(message.toString()).fail();
    }
  }

   * if the primary input succeeds, it is never invoked. If, during the invocation of {@code
   * fallback}, an exception is thrown, this exception is used as the result of the output {@code
   * Future}.
   *
   * <p>Usage example:
   *
   * <pre>{@code
   * ListenableFuture<Integer> fetchCounterFuture = ...;
   *
   * // Falling back to a zero counter in case an exception happens when
   * // processing the RPC to fetch counters.

 * </ul>
 *
 * <p>These features are all optional; caches can be created using all or none of them. By default,
 * cache instances created by {@code CacheBuilder} will not perform any type of eviction.
 *
 * <p>Usage example:
 *
 * <pre>{@code
 * LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
 *     .maximumSize(10000)
 *     .expireAfterWrite(Duration.ofMinutes(10))
 *     .removalListener(MY_LISTENER)